I spent time to experience some variations of the classical T puzzles in here - a kind of dissection/tiling puzzle (Gardner's T, Nob's T, and Asymmetric T). They are 4-piece tangrams. They all give good feeling in experiencing and mathematical aspects.
I really wonder how to compare or how to choose the best one among them, again in experiencing and mathematical aspects.
More generally, is there any criterion to compare tangrams, equal or not equal pieces, for BEAUTY and/or DIFFICULTY in your opinion?
As far I know, there is no exact definition of beauty and difficulty for tangrams. Natively, difficulty means the number of configurations that tangram made. Concept of beauty is quite subjective, for example, it may be the number of configurations with a axis symmetry, or it may be the number of convex polygon configurations, ... .